Development of advanced anion exchange membrane from the view of the performance of water electrolysis cell

Green hydrogen produced by water electrolysis combined with renewable energy is a promising alternative to fossil fuels due to its high energy density with zero-carbon emissions.Among water electrolysis technologies,the anion exchange membrane(AEM) water electrolysis has gained intensive attention and is considered as the next-generation emerging technology due to its potential advantages,such as the use of low-cost non-noble metal catalysts,the relatively mature stack assembly process,etc.However,the AEM water electrolyzer is still in the early development stage of the kW-level stack,which is mainly attributed to severe performance decay caused by the core component,i.e.,AEM.Here,the review comprehensively presents the recent progress of advanced AEM from the view of the performance of water electrolysis cells.Herein,fundamental principles and critical components of AEM water electrolyzers are introduced,and work conditions of AEM water electrolyzers and AEM performance improvement strategies are discussed.The challenges and perspectives are also analyzed.

Electrochemical reconstruction of non-noble metal-based heterostructure nanorod arrays electrodes for highly stable anion exchange membrane seawater electrolysis

Direct seawater electrolysis for hydrogen production has been regarded as a viable route to utilize surplus renewable energy and address the climate crisis.However,the harsh electrochemical environment of seawater,particularly the presence of aggressive Cl^(-),has been proven to be prone to parasitic chloride ion oxidation and corrosion reactions,thus restricting seawater electrolyzer lifetime.Herein,hierarchical structure(Ni,Fe)O(OH)@NiCoS nanorod arrays(NAs)catalysts with heterointerfaces and localized oxygen vacancies were synthesized at nickel foam substrates via the combination of hydrothermal and annealing methods to boost seawater dissociation.The hiera rchical nanostructure of NiCoS NAs enhanced electrode charge transfer rate and active surface area to accelerate oxygen evolution reaction(OER)and generated sulfate gradient layers to repulsive aggressive Cl^(-).The fabricated heterostructure and vacancies of(Ni,Fe)O(OH)tuned catalyst electronic structure into an electrophilic state to enhance the binding affinity of hydroxyl intermediates and facilitate the structural transformation into amorphousγ-NiFeOOH for promoting OER.Furthermore,through operando electrochemistry techniques,we found that theγ-NiFeOOH possessing an unsaturated coordination environment and lattice-oxygen-participated OER mechanism can minimize electrode Cl^(-)corrosion enabled by stabilizing the adsorption of OH*intermediates,making it one of the best OER catalysts in the seawater medium reported to date.Consequently,these catalysts can deliver current densities of 100 and 500 mA cm-2for boosting OER at minimal overpotentials of 245and 316 mV,respectively,and thus prevent chloride ion oxidation simultaneously.Impressively,a highly stable anion exchange membrane(AEM)seawater electrolyzer based on the non-noble metal heterostructure electrodes reached a record low degradation rate under 100μV h-1at constant industrial current densities of 400 and 600 mA cm-2over 300 h,which exhibits a promising future for the nonprecious and stable AEMWE in the direct seawater electrolysis industry.

Towards high-performance and robust anion exchange membranes(AEMs)for water electrolysis:Super-acid-catalyzed synthesis of AEMs

The increasing demand for hydrogen energy to address environmental issues and achieve carbon neutrality has elevated interest in green hydrogen production,which does not rely on fossil fuels.Among various hydrogen production technologies,anion exchange membrane water electrolyzer(AEMWE)has emerged as a next-generation technology known for its high hydrogen production efficiency and its ability to use non-metal catalysts.However,this technology faces significant challenges,particularly in terms of the membrane durability and low ionic conductivity.To address these challenges,research efforts have focused on developing membranes with a new backbone structure and anion exchange groups to enhance durability and ionic conductivity.Notably,the super-acid-catalyzed condensation(SACC)synthesis method stands out due to its user convenience,the ability to create high molecular weight(MW)polymers,and the use of oxygen-tolerant organic catalysts.Although the synthesis of anion exchange membranes(AEMs)using the SACC method began in 2015,and despite growing interest in this synthesis approach,there remains a scarcity of review papers focusing on AEMs synthesized using the SACC method.The review covers the basics of SACC synthesis,presents various polymers synthesized using this method,and summarizes the development of these polymers,particularly their building blocks including aryl,ketone,and anion exchange groups.We systematically describe the effects of changes in the molecular structure of each polymer component,conducted by various research groups,on the mechanical properties,conductivity,and operational stability of the membrane.This review will provide insights into the development of AEMs with superior performance and operational stability suitable for water electrolysis applications.

Pore-Scale Investigation of Coupled Two-Phase and Reactive Transport in the Cathode Electrode of Proton Exchange Membrane Fuel Cells

A three-dimensional multicomponent multiphase lattice Boltzmann model(LBM)is established to model the coupled two-phase and reactive transport phenomena in the cathode electrode of proton exchange membrane fuel cells.The gas diff usion layer(GDL)and microporous layer(MPL)are stochastically reconstructed with the inside dynamic distribution of oxygen and liquid water resolved,and the catalyst layer is simplifi ed as a superthin layer to address the electrochemical reaction,which provides a clear description of the fl ooding eff ect on mass transport and performance.Diff erent kinds of electrodes are reconstructed to determine the optimum porosity and structure design of the GDL and MPL by comparing the transport resistance and per-formance under the fl ooding condition.The simulation results show that gradient porosity GDL helps to increase the reactive area and average concentration under fl ooding.The presence of the MPL ensures the oxygen transport space and reaction area because liquid water cannot transport through micropores.Moreover,the MPL helps in the uniform distribution of oxygen for an effi cient in-plane transport capacity.Crack and perforation structures can accelerate the water transport in the assembly.The systematic perforation design yields the best performance under fl ooding by separating the transport of liquid water and oxygen.

Water Distribution and Removal along the Flow Channel in Proton Exchange Membrane Fuel Cells

Distribution expressions of total gas pressure and partial water vapor pressure along the channel direction were established based on lumped model by analyzing pressure loss in the channel and gas diffusion in the layer. The mechanism of droplet formation in the flow channel was also analyzed. Effects of the relative humidity, working temperature and stoichiometry on liquid water formation were discussed in detail. Moreover, the force equilibrium equation of the droplet in the flow channel was deduced, and the critical flow velocity for the water droplet removal was also addressed. The experimental results show that the threshold position of the liquid droplet is far from the inlet with the increase of temperature, and it decreases with the increase of the inlet total pressure. The critical flow velocity decreases with the increase of the radius and the working pressure.

Ternary layered double hydroxide oxygen evolution reaction electrocatalyst for anion exchange membrane alkaline seawater electrolysis

Anion exchange membrane(AEM)water electrolyzers are promising energy devices for the production of clean hydrogen from seawater.However,the lack of active and robust electrocatalysts for the oxygen evolution reaction(OER)severely impedes the development of this technology.In this study,a ternary layered double hydroxide(LDH)OER electrocatalyst(NiFeCo-LDH)is developed for high-performance AEM alkaline seawater electrolyzers.The AEM alkaline seawater electrolyzer catalyzed by the NiFeCo LDH shows high seawater electrolysis performance(0.84 A/cm^(2)at 1.7 Vcell)and high hydrogen production efficiency(77.6%at 0.5 A/cm^(2)),thus outperforming an electrolyzer catalyzed by a benchmark IrO_(2)electrocatalyst.The NiFeCo-LDH electrocatalyst greatly improves the kinetics of the AEM alkaline seawater electrolyzer,consequently reducing its activation loss and leading to high performance.Based on the results,this NiFeCo-LDH-catalyzed AEM alkaline seawater electrolyzer can likely surpass the energy conversion targets of the US Department of Energy.

Patterned catalyst layer boosts the performance of proton exchange membrane fuel cells by optimizing water management

Mass transport is crucial to the performance of proton exchange membrane fuel cells,especially at high current densities.Generally,the oxygen and the generated water share same transmission medium but move towards opposite direction,which leads to serious mass transfer problems.Herein,a series of patterned catalyst layer were prepared with a simple one-step impressing method using nylon sieves as templates.With grooves 100μm in width and 8μm in depth on the surface of cathode catalyst layer,the maximum power density of fuel cell increases by 10%without any additional durability loss while maintaining a similar electrochemical surface area.The concentration contours calculated by finite element analysis reveal that the grooves built on the surface of catalyst layer serve to accumulate the water nearby while oxygen tends to transfer through relatively convex region,which results from capillary pressure difference caused by the pore structure difference between the two regions.The separation of oxidant gas and generated water avoids mass confliction thus boosts mass transport efficiency.

Ruthenium-lead oxide for acidic oxygen evolution reaction in proton exchange membrane water electrolysis

Developing an active and stable anode catalyst for the proton exchange membrane water electrolyzer(PEM-WE)is a critical objective to enhance the economic viability of green hydrogen technology.However,the expensive iridium-based electrocatalyst remains the sole practical material with industrial-level stability for the acidic oxygen evolution reaction(OER)at the anode.Ruthenium-based catalysts have been proposed as more cost-effective alternatives with improved activity,though their stability requires enhancement.The current urgent goal is to reduce costs and noble metal loading of the OER catalyst while maintaining robust activity and stability.In this study,we design a Ru-based OER catalyst incorporating Pb as a supporting element.This electrocatalyst exhibits an OER overpotential of 201 mV at 10 mA·cm^(-2),simultaneously reducing Ru noble metal loading by~40%.Normalization of the electrochemically active surface area unveils improved intrinsic activity compared to the pristine RuO_(2) catalyst.During a practical stability test in a PEM-WE setup,our developed catalyst sustains stable performance over 300 h without notable degradation,underscoring its potential for future applications as a reliable anodic catalyst.

高质子传导率的GSPEEK凝胶膜制备及其PEMWE性能

磺化聚醚醚酮(SPEEK)质子交换膜一般是将聚醚醚酮(PEEK)先磺化然后再进行溶解流延的方式来制备,存在制备过程复杂和电导率较低等问题.本研究创新性的将磺化与成膜过程集成,一步实现从PEEK到磺化度可控的凝胶质子膜(GSPEEK)的高效制备.GSPEEK膜具有的独特“鱼鳞”状微观形貌,极大提升其质子电导率,在GSPEEK固含量为10%(质量分数)、成膜温度40℃时电导率可达167.0 mS/cm,其质子传导率分别是普通SPEEK膜的3.05倍和商业Nafion 117膜的2.45倍.组装成质子交换膜电解水制氢膜电极(MEA)进行测试,结果表明,当电压为2.4 V时,GSPEKK-10膜的电流密度为1000 mA/cm^(2),相较于普通SPEEK膜和Nafion-117膜的600 mA/cm^(2)、400 mA/cm^(2),其电解水性能得到了大幅度的提升,具有潜在的产业化前景.

基于钛毡的多孔传输层不同参数对PEMWE极化性能的影响

研究了不同参数的阳极多孔传输层在质子交换膜水电解中的极化特性。结果发现,铱钌镀层可降低电解池的欧姆极化和电荷转移极化。同时,钛毡厚度为0.2 mm,通孔面积集中在40μm^(2),孔隙率为60%时,其欧姆极化和传质极化有所降低。基于上述结论,设计了一款性能良好的定制钛毡。在3 A/cm^(2)的电流密度下,该阳极钛毡的水电解电压为2.11 V,而普通钛毡的水电解电压为2.40 V。

Generation of input spectrum for electrolysis stack degradation test applied to wind power PEM hydrogen production

Hydrogen production by proton exchange membrane electrolysis has good fluctuation adaptability,making it suitable for hydrogen production by electrolysis in fluctuating power sources such as wind power.However,current research on the durability of proton exchange membrane electrolyzers is insufficient.Studying the typical operating conditions of wind power electrolysis for hydrogen production can provide boundary conditions for performance and degradation tests of electrolysis stacks.In this study,the operating condition spectrum of an electrolysis stack degradation test cycle was proposed.Based on the rate of change of the wind farm output power and the time-averaged peak-valley difference,a fluctuation output power sample set was formed.The characteristic quantities that played an important role in the degradation of the electrolysis stack were selected.Dimensionality reduction of the operating data was performed using principal component analysis.Clustering analysis of the data segments was completed using an improved Gaussian mixture clustering algorithm.Taking the annual output power data of wind farms in Northwest China with a sampling rate of 1 min as an example,the cyclic operating condition spectrum of the proton-exchange membrane electrolysis stack degradation test was constructed.After preliminary simulation analysis,the typical operating condition proposed in this paper effectively reflects the impact of the original curve on the performance degradation of the electrolysis stack.This study provides a method for evaluating the degradation characteristics and system efficiency of an electrolysis stack due to fluctuations in renewable energy.

Internal Polarization Field Induced Hydroxyl Spillover Effect for Industrial Water Splitting Electrolyzers

The formation of multiple oxygen intermediates supporting efficient oxygen evolution reaction(OER)are affinitive with hydroxyl adsorption.However,ability of the catalyst to capture hydroxyl and maintain the continuous supply at active sits remains a tremendous challenge.Herein,an affordable Ni2P/FeP2 heterostructure is presented to form the internal polarization field(IPF),arising hydroxyl spillover(HOSo)during OER.Facilitated by IPF,the oriented HOSo from FeP2 to Ni2P can activate the Ni site with a new hydroxyl transmission channel and build the optimized reaction path of oxygen intermediates for lower adsorption energy,boosting the OER activity(242 mV vs.RHE at 100 mA cm-2)for least 100 h.More interestingly,for the anion exchange membrane water electrolyzer(AEMWE)with low concentration electrolyte,the advantage of HOSo effect is significantly amplified,delivering 1 A cm^(-2)at a low cell voltage of 1.88 V with excellent stability for over 50 h.

High-performance porous transport layers for proton exchange membrane water electrolyzers

Hydrogen is a favored alternative to fossil fuels due to the advantages of clean-liness,zero emissions,and high calorific value.Large-scale green hydrogen production can be achieved using proton exchange membrane water electrolyz-ers(PEMWEs)with utilization of renewable energy.The porous transport layer(PTL),positioned between the flow fields and catalyst layers(CLs)in PEMWEs,plays a critical role in facilitating water/gas transport,enabling electrical/thermal conduction,and mechanically supporting CLs and membranes.Superior cor-rosion resistance is essential as PTL operates in acidic media with oxygen saturation and high working potential.This paper covers the development of high-performance titanium-based PTLs for PEMWEs.The heat/electrical con-duction and mass transport mechanisms of PTLs and how they affect the overall performances are reviewed.By carefully designing and controlling substrate microstructure,protective coating,and surface modification,the performance of PTL can be regulated and optimized.The two-phase mass transport char-acteristics can be enhanced by fine-tuning the microstructure and surface wettability of PTL.The addition of a microporous top-layer can effectively improve PTL|CL contact and increase the availability of catalytic sites.The anti-corrosion coatings,which are crucial for chemical stability and conductivity of the PTL,are compared and analyzed in terms of composition,fabrication,and performance.

Interfacial engineering of atomic platinum-doped molybdenum carbide quantum dots for high-rate and stable hydrogen evolution reaction in proton exchange membrane water electrolysis

Platinum(Pt)-based electrocatalysts remain the only practical cathode catalysts for proton exchange membrane water electrolysis(PEMWE),due to their excellent catalytic activity for acidic hydrogen evolution reaction(HER),but are greatly limited by their low reserves and high cost.Here,we report an interfacial engineering strategy to obtain a promising low-Pt loading catalyst with atomically Pt-doped molybdenum carbide quantum dots decorated on conductive porous carbon(Pt-MoCx@C)for high-rate and stable HER in PEMWE.Benefiting from the strong interfacial interaction between Pt atoms and the ultra-small MoCx quantum dots substrate,the Pt-MoCx catalyst exhibits a high mass activity of 8.00 A·mgPt−1,5.6 times higher than that of commercial 20 wt.%Pt/C catalyst.Moreover,the strong interfacial coupling of Pt and MoCx substrate greatly improves the HER stability of the Pt-MoCx catalyst.Density functional theory studies further confirm the strong metal-support interaction on Pt-MoCx,the critical role of MoCx substrate in the stabilization of surface Pt atoms,as well as activation of MoCx substrate by Pt atoms for improving HER durability and activity.The optimized Pt-MoCx@C catalyst demonstrates>2000 h stability under a water-splitting current of 1000 mA·cm^(−2)when applied to the cathode of a PEM water electrolyzer,suggesting the potential for practical applications.

Numerical Investigation on the Effects of Design Parameters and Operating Conditions on the Electrochemical Performance of Proton Exchange Membrane Water Electrolysis

Proton exchange membrane electrolysis cell(PEMEC)is one of the most promising methods to produce hydrogen at high purity and low power consumption.In this study,a three-dimensional non-isothermal model is used to simulate the cell performance of a typical PEMEC based on computational fluid dynamics(CFD)with the finite element method.Then,the model is used to investigate the distributions of current density,species concentration,and temperature at the membrane/catalyst(MEM/CL)interface.Also,the effects of operating conditions and design parameters on the polarization curve,specific electrical energy demand,and electrical cell efficiency are studied.The results show that the maximum distribution of current density,hydrogen concentration,oxygen concentration,and temperature occur beneath the core ribs and increase towards the channel outlet,while the maximum water concentration distribution happens under the channel and decreases towards the channel exit direction.The increase in gas diffusion layer(GDL)thickness reduces the uneven distribution of the contour at the MEM/CL interface.It is also found that increasing the operating temperature from 323 K to 363 K reduces the cell voltage and specific energy demand.The hydrogen ion diffusion degrades with increasing the cathode pressure,which increases the specific energy demand and reduces the electrical cell efficiency.Furthermore,increasing the thickness of the GDL and membrane rises the specific energy demand and lowers the electrical efficiency,but increasing GDL porosity reduces the specific electrical energy demand and improves the electrical cell efficiency;thus using a thin membrane and GDL is recommended.

A systematic review of system modeling and control strategy of proton exchange membrane fuel cell

The proton exchange membrane fuel cell,as a novel energy device,exhibits a wide array of potential applications.This paper offers a comprehensive review and discussion of modeling and control strategies for fuel cell systems.It commences with a concise introduction to the structure and principles of fuel cells.Subsequently,it outlines modeling approaches for various fuel cell subsystems,encompassing the fuel cell stack,air supply system,hydrogen supply system,thermal management system,and water management system.Following this,it conducts a comparative analysis and discussion of prevalent control strategies for the aforementioned subsystems.Lastly,the paper outlines future research trends and directions in the modeling and control strategies of fuel cells.The aim of this paper is to provide ideas and inspirations for the design and management of membrane fuel cell systems from control aspects.

The influence of patterned microporous layer on the proton exchange membrane fuel cell performances

The ordered membrane electrode assembly(MEA)has gained much attention because of its potential in improving mass transfer.Here,a comprehensive study was conducted on the influence of the patterned microporous layer(MPL)on the proton exchange membrane fuel cell performances.When patterned MPL is employed,grooves are generated between the catalyst layer and the gas diffusion layer.It is found that the grooves do not increase the contact resistance,and it is beneficial for water retention.When the MEA works under low humidity scenarios,the MEA with patterned MPL illustrated higher performance,due to the reduced inner resistance caused by improved water retention,leading to increased ionic conductivity.However,when the humidity is higher than 80%or working under high current density,the generated water accumulated in the grooves and hindered the oxygen mass transport,leading to a reduced MEA performance.

SPEEK/PEI@ILs复合质子交换膜的制备及PEMWE性能

以磺化度为75%的磺化聚醚醚酮(SPEEK)为原料,加入聚醚酰亚胺(PEI)和离子液体(ILs)制备SPEEK/PEI@ILs酸碱复合膜用于质子交换膜电解水制氢(PEMWE)中.研究复合膜的吸水率、溶胀度、质子电导率、热稳定性和相应的PEMWE性能.结果表明,SPEEK/PEI@ILs复合膜与商业Nafion117膜相比,具有相近的质子电导率和溶胀度,说明PEI的加入,增强了复合膜的尺寸稳定性.将SPEEK/PEI@ILs复合膜制备成膜电极并测试PEMWE性能,1 A/cm2电流密度下槽电压为2.75 V,在0.5 A/cm^(2)@1.96(±0.03)V条件下能稳定运行10 h.

面向波动可再生能源的质子交换膜电制氢系统最优压强运行

为提升质子交换膜电制氢系统在波动可再生能源输入下的制氢效率,提出面向最大效率的质子交换膜电制氢系统最优压强运行模式。介绍质子交换膜电制氢系统,提出基于压强控制的协调运行原理;对质子交换膜电制氢系统的压强特性和功率特性进行建模,从而建立面向最大效率的压强优化模型。在波动电流输入算例下检验最优压强运行模式的制氢效果,结果表明,相较于恒定压强模式,最优压强运行模式下的质子交换膜电制氢系统平均制氢能耗得到有效降低,系统性能得到明显提升。

基于蜂窝仿生流场的质子交换膜燃料电池的性能研究及优化

为了增强质子交换膜燃料电池(PEMFCs)内部燃料分布的均匀性与水管理能力,本文研究了一种新型的基于仿生结构的蜂窝仿生流场。首先,根据蜂窝结构特征,搭建出三维多相流非等温几何模型并确立PEMFC的数学模型;其次,采用计算流体动力学Fluent软件对模型进行无关性与有效性验证,并对蜂窝仿生流场和常规平行流场的电池性能和燃料分布进行了模拟分析;最后,对比极化性能、气体流速分布、燃料与液态水组分浓度和电流密度分布,验证了蜂窝仿生流场设计的有效性。研究结果表明:采用蜂窝仿生流场的电池峰值功率密度比常规平行流场高15.6%,其内部水管理能力和燃料分布均匀性均强于平行流场;左端进气的蜂窝仿生流场比采用上端进气的蜂窝仿生流场在气体通路内具有更均匀的气体压力,可有效避免流道内产生局部涡流,其峰值功率密度可以达到0.3933 W/cm2。